>From my observation, most Splittie and Bay campers tend to have dried out
rubber body to window seal gaskets. 
I stopped into the glass shop that is ordering the grey rubber "spline"
gasket seal material that I hope to use around the camper windows in the '67
resto project. After asking if there was a known method for revitalizing
older rubber (for example the OEM westy window rubber) I was told that
soaking the rubber over night in *sugar beet based* waterless NONPETROLEUM
based hand cleaner does a pretty decent job. After the overnight soak the
gasket stuff can be "worked" and then thoroughly  rinsed in clear water and
then dried.
 I was warned to avoid the citrus based "orange" and gritty hand cleaners
due to the level of acidity. I was also warned to avoid PETROLEUM based hand
cleaners. Read the labels if you choose to try this suggestion.
This whole procedure might have no, very little, or positive effects on the
gasket seals but I figured it's worth a try. I had never heard of this
method before.
-ellis\